For example, when communication is performed between devices connected to a network, a receiver device and a transmitter device often have asynchronous clocks and, in addition, different clock frequencies due to different operating environments (e.g., power supply noise, temperature, etc.). Therefore, the receiver device needs to perform synchronization based on received data so as to perform data communication between these devices. This process is commonly called timing recovery, data clock recovery or the like.
In typical timing recovery, a clock is generated in a receiver, a phase difference between the clock and received data is detected, and the frequency or phase of the clock is adjusted, depending on the detected phase difference, thereby generating a clock having a phase appropriate for data reception. Thereafter, the clock thus adjusted is used to latch data to perform data reception. Also, by continually and repeatedly performing the clock adjustment, the phase of the clock is always adjusted to an ideal position even if the phase of received data varies, whereby avoiding violation of a setup constraint and a hold constraint of a flip-flop which receives data.
There is an example of a timing recovery circuit which performs such timing recovery as follows (see, for example, PATENT DOCUMENT 1). Specifically, a determination circuit samples a multiphase clock signal at rising edges of received data, and from the resultant sampled state, determines an optimum sampled clock signal for reproduction of the received data. The sampled clock signal is supplied via a clock select circuit to a sampling circuit. Thereafter, the sampling circuit latches the received data in accordance with the sampled clock signal supplied from the clock select circuit.
Thus, an optimum clock is selected in view of a relationship between the clock and a transition point of received data, and the received data is latched in synchronization with the clock, whereby data whose phase varies due to jitter or the like can be correctly received.